The present invention relates to a door opening and closing device which opens and closes a door relative to a base member through a rotational mechanism and latch mechanism.
In this specification, it should be noted that the term “base member” is intended to include various types of housing main members, housing and the like. It should also be noted that the term “door” is intended to include a lid, blocking plate or the like. Additionally, it should be noted that the term “latch mechanism” has substantively the same meaning as a lock mechanism.
FIGS. 10(a), 10(b) show a door opening and closing device disclosed in Japanese Patent Publication No. 2003-129742. FIG. 10(a) shows a closed position of the door while FIG. 10(b) shows an open position of the door.
In this door opening and closing device, a door 3 is switched from a closed position to an open position relative to a base member 2 through a rotational mechanism, and releasably locked through a latch mechanism in the closed position. In this arrangement, the upper side of the base member 2 is bordered by a flange portion 26. The side walls 23 of the base member 2 are such that back sides 23b overhang the exterior to a greater extent than the front sides 23a, and window portions are formed through the projecting end faces. The door 3 includes supporting arms 31 which extend out through the window portions from the inside of the base member 2. The rotational mechanism is such that arc-like gear portions 37 are provided in the arms 31 of the door 3, while a rotating gear 7 is provided at the center of the arc of the gear portions 37. The base member 2 includes internally-toothed gear portions 27a provided in arcuate ribs 27 which engage the gear portions 37; and second fixing gear portions 28 provided inside the first fixing gears 27a and engaging the rotating gear 7.
The rotating gear 7 is mounted on an output shaft of a damper means 6. Also, a latch mechanism 4 is, for example, a “push-push” locking mechanism (which may also be referred to as a push-to-open mechanism or push-to-lock/push-to-open mechanism) attached to the base member 2.
When the door 3 is pivoted from its, open position to its closed position against an urging force of an urging or biasing means S, the latch mechanism 4 locks by engaging an engagement member 34 additionally provided in the door 3, and unlocks by pushing the door 3 further in the closing direction. In this particular arrangement, the urging means 5 is a coil spring member. One end Sa of the urging means S is connected to a projection 29 provided on the base member while the another end Sb of the urging means S is connected to shaft portions 35 provided on an arm 31 of the lid or door 3.
In the door opening and closing device of the above-mentioned Japanese Patent Publication No. 2003-129742, the door 3 is open and closed via movement along the track of the inner periphery (first fixing gear portions 27a) of each arched rib 27 of the rotational mechanism. More specifically, when the door 3 is rotated from the closed position to the open position, or from the open position to the closed position, the rotational fulcrum of the door 3 is moved downward or upward according to the first fixing gear portion 27a of the arched rib 27.
With this arrangement, the rotational mechanism can control the volume of an overhung portion from the inside of the base member 2 of the door 3 in the open position, and provide an excellent operation due to the engagement of the gears with the braking of the damper means 6. However, in this rotational mechanism, each arc-like gear portion 37 on an arm is engaged with the first fixing gear portion 27a on an arched rib which is concentric with the second fixing gear portion 28. With this the opening and closing track of the door cannot be freely determined, and also the necessarily precise relationship between the gears is hard to obtain. If this precise relationship between the gears cannot be obtained, a reliable operation cannot be provided.
Also, the first fixing gear portion 27a provides the arched rib 27 on each side of the base member 2, a tooth form or rack is formed on the inner periphery face of the arched rib 27, and the second fixing gear portion 28 comprises a rotatable spur gear. As a result, when the first fixing gear portion 27a or the second fixing gear portion 28 is integrally molded with the base member 2, the molding becomes complicated and expensive, and as a result the precision necessary in the engagement between the gears is hard to maintain.
Another problem resides in that, when the door receives a large load downward in the closed position, the second fixing gear portion 28 bears an excessive load and this may cause damage. Obviously, as a device, the volume of the overhung portion from the inside of the base member 2 of the door 3 in the open position is preferably reduced. On the other hand, the latch mechanism is such that the door 3 includes the engagement member 34 which projects away from the inner face on the free edge of the door, and is engaged and disengaged through the engagement member 34. Accordingly, when the door is open, the engagement member 34 projects into the opening and as a result, the appearance is deteriorated, and also the engagement member 34 can interfere with articles which are removed from or placed into the base member 2.
Objects of the present invention are to solve the above-mentioned problems, and provide a rotational mechanism which facilitates integral molding with the base member while maintaining dimensional precision, and allows the volume of the overhung portion from the inside of the base member of the door to be reduced when the door is open, especially by simplifying the mechanical structure. Especially, in the structure wherein the latch mechanism is additionally provided on the base member side, the latch mechanism can eliminate the use of a conventional engagement member which projecting from the door, i.e., the latch mechanism can adopt a difference in level configuration such as a depression or L shape or the like, the appearance of which can be easily maintained and the engagement member can be eliminated, so that the overall appearance of the latch mechanism can be improved.
Further objects and advantages of the invention will be apparent from the following description of the invention.